The present invention relates to a suction type traveling carriage capable of traveling over walls and ceilings.
Well-known in the art is a carriage with magnetic wheels which is attracted to walls and ceilings by magnetic forces of the magnetic wheels and travels thereover. Apparently, such carriage with magnetic wheels can be used only when the walls and ceilings are made of magnetic materials. Therefore, there has been a strong demand for traveling carriages capable of traveling over walls and ceilings even when the latter are not made of magnetic materials.
To overcome the above problem, there has been devised and demonstrated a traveling carriage with a plurality of movable arms each having at its end a suction cup adapted to be attracted to walls and ceilings when it is evacuated and adapted to be released therefrom when its internal pressure is restored to a normal level. With such suction type traveling carriages, first all the suction cups are evacuated for attraction of the carriage to the wall or ceiling. Next the suction cups are grouped into a suitable number of groups and while internal pressures of the suction cups in one group are restored to a normal level, they are displaced in a direction of travel. After the displacement, they are evacuated again and are maintained at the positions. Then, the suction cups of another group are actuated in like manner and the arms are retracted to drag the carriage in the direction of travel. These steps are sequentially repeated so that the suction cups are displaced in a walking manner and consequently the carriage is moved over the wall or ceiling while being attracted thereto.
There has been devised and demonstrated another vacuum type traveling carriage in which the carriage itself is in the form of a vacuum chamber adapted to be selectively evacuated or restored to a normal level and in which wheels are disposed. While the carriage itself is attracted to a wall or ceiling, the wheels within the carriage are driven to move the carriage over the wall or ceiling.
However, the suction type traveling carriages of the type described above have extreme difficulty in increasing its velocity because the displacements are intermittent and need very complex valve-switching operations. While the suction cups in one group are released from the vacuum and are advanced forwardly, the remaining groups of suction cups are evacuated for attraction of the carriage to the wall or ceiling so that the carriage must be equipped with a number of suction cups which is almost twice as many as minimum number of suction cups required for attaining secure contact of the carriage with the wall or ceiling. Furthermore the same number of means for walking of the carriage is required. As a result, the carriage becomes complex in construction, heavy in weight, large in size and very expensive. Moreover in order to make the carriage turnable, its construction becomes further complicated.
In the case of the carriage in the form of a vacuum chamber having driving wheels therein, the carriage encouters a considerably high degree of resistance when it travels over a wall or ceiling. As a result, it becomes extremely difficult to simultaneously accomplish attraction of the carriage to the wall or ceiling as well as traveing thereof so that the carriage capable of these simultaneous operations will become complicated in construction.
In view of the above, a primary object of the present invention is to provide a suction type traveling carriage which is simple in construction yet capable of ensuring secure attraction of the carriage to a wall or ceiling while incresing the velocity of the carriage.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of some embodiments thereof taken in conjuction with the accompanying drawings.